Wireless capsule technology: Remotely powered improved high-sensitive barometric endoradiosonde

Abstract

In this paper an improved design of an RFID powered swallowable barometric endoradiosonde (ERS) is presented. The ERS consists of a micro fabricated capacitive sensor printed in gold on Polycaprolactone (PCL) on which a transponder chip design in 0.35μm AMS technology is in-plane bounded to the PCL substrate. The implantable or inside the body, transponder (tag) is powered by the external reader at 900MHz through inductively coupled antennas. The tag performs the capacitance to frequency conversion and transmits data back to the reader using load-shift keying (LSK) modulation. The ERS can measure the sensor output frequency with an INL error of 0.4%, sensitivity (Δf/ΔP) of -6.12MHz/kPa, occupies a volume of 1mm3 (transponder only), consumes, 400μW and 360μW for, respectively, dynamic and static power. The sensor has an accuracy of ± 0.1kPa, works in the pressure range of 0-1.99kPa (0-15mmHg). The readout circuit has a ±1.84kHz resolution.